1. Field of the Invention
This invention relates generally to clipper circuits and, more particularly, to a resonant filtered clipper circuit which utilizes resonant short circuiting at a clipping point to eliminate specific harmonics.
2. Description of the Prior Art
In the prior art, the most widely used approach to limiting an audio signal has been by means of peak clipping. This technique, however, suffers from the disadvantage that harmonics above 15 KHz are produced. This can result in audible distortion after transmission. In addition, the harmonics may interfere with the synchronizing pilot signal (19 KHz) resulting in loss of stereophonic reception. To help overcome the problems associated with the generation of harmonics, a sharp low-pass filter is employed to assure that the audio signal applied to the stereo generator has little or no high frequency components; i.e. above 15 KHz. Unfortunately, such filters exhibit phase shift and cut-off characteristics which creates ringing at the output.
The above problems have been solved through the use of clipper circuits which generate little or no harmonic components at 19 KHz and 23 KHz to 53 KHz. Special and elaborate filters have been developed using active filter designs, clipping the ringing and refiltering. While generally successful, such circuits are extremely complex and, therefore, costly.